Magnetic field sensor devices in the form of flux gates are discussed in the related art. In the case of flux gates, magnetically soft cores are periodically driven to an opposite saturation. The cores are wound with two receiver coils wound in opposite directions, so that, in the absence of a field, the induced voltages in both coils cancel each other. If a magnetic field is then applied, the vectorial component in the direction of the cores produces a resulting signal in the receiver coils that is proportional to the applied field.
German patent document DE 10 2007 032 299 A1 discusses such a magnetic field sensor device having a flux gate sensor, which is made up of an excitation coil, an induction coil and a magnetic core, the core consisting of a layer stack of magnetically soft layers disposed in alternation next to each other, and antiferromagnetic layers pinning them.
In the field of magnetic data storage a method for the direct variation of the magnetization of a nanowire by electrical current is discussed in Parkin et al, Science 11, Vol. 320, No. 5873, pages 190-194, April 2008. According to this method, different bits are serially written in a nanowire having a width of a few 100 nm, and read out again by local spin valves.